Transcript for President Obama Responds to the Execution of James Foley

This is an ABC news. Now reported George Stephanopoulos. And we're coming on the air right now because President Obama is about to speak from Martha's Vineyard. -- the execution of American journalist James Foley by the Islamic militants fighting in Iraq and Syria. Foley was reporting for the online news service global post when -- kidnapped in northern Syria on Thanksgiving Day 2012. In the video released by the militant group vices which we will not show info just these still photos that we're gonna show you right now. He's forced to read a letter condemning America before the hooded executioner speaking with a British accent he heads. In retaliation he said for US airstrikes in Iraq. The Milton also placing holding another American journalist Steven Jewell -- -- went missing in Syria last year. -- -- state declared the executioner will depend on president Obama's next move. ABC's chief White House correspondent John -- with the president John US intelligence has concluded sadly. That this video is authentic. US intelligence confirmed the authenticity of the video this morning and unfortunately George it was not a surprise a senior US official tells me. That the US government had received a warning. From the captors from -- captors saying that he would be -- -- and in retaliation for US airstrikes in Iraq. So apparently they carried through on that threat. -- George the president spoke to -- parents short time ago -- told right now he will offer a message of condemnation and resolve condemning the attacks. And resolve to continue the fight against this terrorist group saying this act of terror. This act of horror. Confirms the very reasons for why the US is involved in this campaign against -- in Iraq. And we will hear from police parents after the president. -- and John -- speaking to reporters outside their home here comes the president now. -- -- -- Today the entire world is appalled. By the brutal murder Jim Foley by the terrorist group -- -- as a journalist. Whose son. A brother. And a friend. He reported from difficult and dangerous places bearing witness to the lives of people. A world away. -- taken hostage nearly two years ago in Syria and it was. Courageously -- reporting of the time on the conflict there. -- was taken from us an act of violence that shocks the conscience of the entire world. He was forty years old. One of five siblings. Of saga of a mom and dad who worked tirelessly for his release. Earlier today I spoke to the -- and told them that we are all heartbroken at their loss and join them. In honoring Jim and all that he did. -- Jim Foley's life stands in stark contrast. To his killers. Let's be clear but -- They have rampaged across cities and villages killing innocent on -- civilians and cowardly acts of violence. They abduct women and children. And subject them to torture. And rape. And slavery. -- murdered Muslims. Both Sunni and -- by the thousands. The target Christians and religious minorities. Driving them from their homes. Murdering them when they can't. For no other reason. And day. Practice a different religion. They declare their ambition to commit genocide. Against an -- people. So -- soul speaks for -- all religion. The victims are overwhelmingly Muslim. And no faith teaches people the massacre in -- No just god would stand for what they did yesterday and what they do every single. Parcel has no ideology. -- many valued at human beings. Their ideology was bankrupt. They may claim. Out of expediency Rivera -- -- the United States. Where the west but the fact is -- terrorism rise their neighbors. And offer them nothing but an analyst slavery to -- -- -- And the collapse of any definition of civilized behavior. And people like this. Ultimately failed. They fail because the future is one by those who build and not destroy. The world was shaped by people like Jim following. And the overwhelming majority of humanity were appalled by those who kill them. United States Americo -- will continue to do what we must do to protect our people. We will be vigilant and we will be relentless. When people harm Americans anywhere. We do what's necessary to see the justice is done. And we act against -- Standing alongside others. The people of Iraq who -- our support are taking the fight -- Must continue coming together to expel these terrorists from their community -- The people of Syria the story. Jim Foley told. Do not deserve to live under the shadow of a tyrant or terrorists. Never support in their pursuit. For the future rooted in dignity. From governments and peoples across the Middle East. They're asked to be a common effort to extract this cancer so that it does not spread. That's to be a clear rejection. Of these kind of nihilistic. Ideologies. One thing we can all agree on is that a group like arsenal has no place. In the 41 century. Friends and allies around the world. We share a common security and a common set of values that are rooted in the opposite of what we saw yesterday. And we will continue to confront this hateful terrorism and replace it with a sense of hope. And stability. That's what Jim Foley stood for. The man who lived his work. Who courageously told the stories of -- fellow human beings. Who was liked and loved by friends and family. Today the American people -- say a prayer for those who love Jim. All of us feel -- of his absence. All of us mourn his loss. We keep in our prayers those other Americans were separated from their families. We will do everything that we can to protect our people. And the timeless values that we stand for. May god bless and keep -- memory and may god bless the United States of America. President Obama clearly seething with anger. Speaking out against the execution of James -- -- is appalled and shocks the conscience. The entire world by these -- -- militants right now. In Iraq -- here I'm joined by our chief investigative correspondent. Brian Ross and invited -- speaking out against -- they speak for no religion at all that this -- become that. Perhaps the most fierce and while finance fighting group terrorist group in the world. Absolutely as the president said no just god understands what happened there. They have again and again and enable them out huge amounts of money. Recruiting thousands of fighters. Including from the west to join in their battle first in Syria now in Iraq it's almost unaccountable and -- from the west we have learned that executioner. British accent British accident -- cameras gone back to deal in this. In London today in fact today they're poring over the video looking for clues as to the identity of this execution are looking closely at his eyes his hands. And most -- -- you -- George his voice which seems to have either an east londoners South London distinctive accent. And the British authorities are comparing that voice to voice tracks they have of British detainees who were in Guantanamo and others who they believe have gone to Syria and enjoy nicest ABC's chief. -- affairs correspondent Martha Raddatz also in the -- the president not backing down one bit Martha. Saying -- -- will do what it must do we will be vigilant he said and relentless. And clearly these airstrikes will continue and they have made progress in Iraq. Yesterday the Pentagon saying that crisis morale is suffering their competency and capacity has been damaged but the president has said it again and again that the strikes will not solve the problem. -- to read it to Brian -- thank you very much for -- we do want to show. James -- -- as the president said he spoke with -- earlier today and they spoke to reporters outside their home in -- -- just moments ago. We're very proud of GM in he was -- courageous. Fearless. Journalist. Very compassionate American and I mean the best of America. And he always hopeless. It is -- he would come home that was his pulp and he sustained all the others who with -- really without hope. But before coming home you want to support his fellow inmate who was always -- first skyline. Via. One that would take the bullet first the woman who would speak to the guards about inequities -- who he was. Was never slacker he was always the disputed. Apparently. Asked the student guy you know which is past equity. Wanted to do for others that we're going to do -- journalists. We also we also appreciate the tremendous number of prayers that we know we see -- -- received throughout all of our communities. Dayton -- has said in Libya in -- we are very sure now that. He could feel the prayers and we think his strange team from -- strength what we know it. I'm as an Arafat and his. President Obama said the thoughts and prayers of America the defendant James from the today. That's all for us right now we're gonna continue -- -- this special report on life. -- will be back with a full report later on world news and you get the latest news any time I starring this story on the ABC news mobile app along with personalized alerts throughout the day. I'm -- Stephanopoulos you have a good. And I -- Martha Raddatz with continuing coverage on the execution of James Foley and the statement just a while ago. By President Obama I want to bring in our chief White House correspondent John Carl. John you mentioned that there was a warning to the White House before this execution can you tell us anymore about that how they got that warning. Well we know that the warning was not through public channels markets there were some kind of -- Of a private channeled directly to the captors of of mr. Foley and this morning I'm told was very recent. No real time to act on it anyway not necessarily that they would have. But when -- the execution when this video appeared it was certainly no surprise. It took a little while for the intelligence community to. Formally authenticated but but they they really knew that this was this was the real deal when they sought and as you know the president was briefed on this. Almost in real time he was briefed while he was flying. On air force warned. Two to the rest of his vacation here in Martha's Vineyard and this I can tell you right now is front and sensor. Of the -- president's agenda right now when you saw I think some of the most passionate words we have seen from the president. On the issue of terrorism period sense that the beginning -- presidency. And and we've been conducting these airstrikes for almost two weeks now and probably close to a hundred airstrikes but the president has said again and again. That will not solve the problem of crisis he said one of the mission's goals is to contain ices. So what else might they do John. Well it did they -- that key factor here now is getting international focus on this group and actually -- to the president will be chairing. A meeting of heads of states members of the UN Security Council in just a few weeks. And the number one issue on the agenda for that summit of world leaders members of the Security Council. Will be. Fighting foreign terrorists and of course from center of that. Fighting crisis. But also major focus on the Iraqi Government the message. From the White House over and over again on this is that as you said airstrikes alone will not defeat this group the United States alone will not defeat this group. This will take an international effort I've not heard a lot of specific ideas however beyond. Urging Iraqis to to take the fight diocese and continuing this campaign. Air strikes I want to bring in Brian -- -- chief investigative. Reporter Brian this this international efforts certainly right now. Involves the British because of that British accent what they're finding. About that ex commissioner. That's right Martha in fact British authorities tell us there could be as many as 250. British citizens who have gone to fight in Syria and many of them if not most of them a win the crisis group. Clearly the executioner in the video that shows that. Death of James Foley spoke with a distinctive British accent people who study this say he is a native English speaker. This is of great concern Britain and they are going through now a database of voices they have brits who are held as detainees in Guantanamo. And others they believe have gone off to the Syria trying to figure out the identity. Of the person who took the knife to the throat of Jim Foley. And I also want to bring in Terry Moran our chief foreign correspondent who is in Iraq and Terry you've been on the ground. With the Kurdish soldiers trying to push back the prices militants and they have made progress. Dana and mark one of the bank you know right up the back is that they would not have been able to gain an -- Despite the the legendary bravery of the murders occurred soldiers -- our call. Without US air -- it was US air that while the road. And made it possible cook. The Kurds and Iraqi special forces to their -- Mosul dam so -- big increase for our. 1 other -- you hear throughout this week and I would hear in June. What I this went down to Mosul an island you hear -- again you even know -- it is. -- -- -- And -- -- -- -- and congress is these increases and these guys are -- -- -- -- -- unimaginable. Brutality and who have them there are no boundaries and no order. 100 and has collected so hard to -- -- group. Is that they don't see Iraq. We're hearing anymore they just see the Islamic state in at least it did very well funded -- very well armed. And -- there have been put back on their heels and that is. An air strike and -- alcohol lock -- popular support. Among disenchanted Sunnis who believe that that debt crisis is there -- regaining dignity and power in this part of the war. About one -- it occurred to me with the president and what he was saying and what you're saying Terry is how bad they are and how extreme they are. He was clearly trying to reach out to the rest of the population. Possibly for another Sunni awakening during the war in Iraq when -- got together and tried to push out these people. Absolutely -- tremendous amount of war behind the scenes going -- In an attempt to reach those tribal leaders in the reignite the Sunni awakening -- meeting in Jordan bleeding from Turkey. So I was in an office where one of the -- their officers. But I would -- actually called a local C. So cliche and kids who come to our -- but it was now within the heart and ugly facts. That there are many on the leaders and ordinary. Who are supporting actors in these areas despite his unimaginable weapons -- savagery. In in some -- The atrocities. There it. Now -- holy family has suffered in the thousands upon thousands cheering him back to film the suffered. Are kind of marketing tool that -- is using. This show the people of this area we are for road -- beyond imagination and we will fight for this and people like no one else. And they are young -- broken by years of war and the current funding from gulf Arab states -- Well this is certainly the first terrorist attack directed. At Americans -- ices this could be. A very long fight for more on this joined Diane -- -- -- and -- Diane Sawyer on world news tonight have a good day.

This transcript has been automatically generated and may not be 100% accurate.

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